216 
MINUTES OF PEOCEEDINGS OF 
Methods of Construction . 
Let ns now consider the methods of construction. There is little 
doubt but that by casting a gun in one mass much time and expense in 
manufacture is saved, and that many difficulties experienced in making 
guns in different parts are avoided. At the same time it has not yet been 
proved that a material of sufficient strength, combined with uniformity in 
quality, can be obtained for casting into heavy ordnance, which will be 
subjected to the strains of large charges of powder. Cast-iron is too un¬ 
certain in character, bronze is too soft and costly, and steel, as I before 
pointed out, is very expensive; it is a dangerous material when fractured, and 
has not yet been sufficiently tried to prove its fitness for very large guns (of 
over 7" calibre). 
Another method is to form the gun out of one solid forging, and this 
has been strongly advocated, but has also been utterly condemned by good 
authorities on the subject.* Lor guns of very small calibre, it has been 
adopted -with some success, but when a piece weighing many tons is required, 
it is now pretty generally admitted that this plan will not give the required 
results. Experiments have shewn that the strength of a forging, like that 
of a casting, is less as its size increases; but besides this, some parts of a 
heavy forging will in most cases be more soundly worked than others, and 
haws, often running in the worst direction, and which cannot sometimes be 
detected until too late, will occur. 
Another method is to build up or construct a gun out of a number of 
distinct pieces, and by this plan several important advantages are obtained. 
1st, The parts may be of such a size that their soundness may be depended 
upon. 2nd, Different materials may be used, each being placed at a part of 
the gun where its peculiar properties are most required. 3rd, The materials 
may be applied in such a manner that their particles or fibres may run in a 
direction most favourable for resistance to the strains to which they will 
be respectively subjected. 4th, That the thickness of metal can be made 
up of a number of separate layers or tubes placed over one another 
with regulated tension, so that each may take its due share of strain. There 
is one most important condition that must not be neglected in building up 
a gun, viz. to provide against the separation of the different parts, for no 
matter what materials are used, the gun will have little endurance if the 
different portions are liable to be shaken asunder by the shocks of successive 
discharges, or by the blows of an enemy’s shot. It must also be obvious 
that a gun constructed out of a few large heavy pieces will be less liable to 
destruction, from the causes just stated, than one consisting of a large 
number of smaller and lighter parts. 
We have obtained in this country considerable experience in the manufac¬ 
ture of built-up guns; not, as might have been foreseen, without many 
disappointments and much expenditure of both time and money. We are 
not perhaps indebted to any individual for our present system of building 
Mallet, Armstrong, Anderson, American authorities, &c. 
